Seismograph



March 16, 1937. w. BLAU Er Al.

sEIsMoGRAPH Filed July 29, 1932 2 Sheets-Sheet 1 M1791( Zizo. INVENToRs zo m ZWTTORNEY- Patented 16,1193? t I i ulsurliov STATES PATENT .oi-rice p SEISMOGRAPH Application July 29, 1932, Serial No. 626,132

4 claims. (ci. '177-352 .i

This invention relates to improvements in seisstantially horizontal position from the frame I8 mographs. The invention will be fully underby means of a-hinge 41. stood from the' following description taken in The center-piece is adjustable from the ex connection with the accompanying drawings in terior of the caseby means of a. screw 50. The

5 which latterscrew 50 carries at its'lower end a collar 5I 5 Fig. 1 is a perspective view of the device with which protrudes through an elongated slot. 52 in the casing removed; the center-piece 46. The collar 5I has set screws Fig. 2 is a longitudinal sectional view taken 54 adapted t0 engage the under Side of the alongl the line II-II of Fig. 3; center-piece I6. The upper end of the screw l Fig. 3 is a longitudinal sectional view taken 50 Aplotllldes through an opening in the Closure 10 along the line III-III of Fig. 2; 2 and-terminates in a hand wheel 5.5 upon the Fig. 4 is a transverse sectional view taken exterior of the Casing The Screw extends ro-v along the line IV-IV of Fig. 3; and' .tatahly through a suitable gland 56 which seals Fig. 5 is a transverse sectional view taken the opening through the closure 2. An indicatalong the line V-V or Fig. 2. ins bar 51 projects upwardly rigidly from the 15 Referring particularly to the drawings, refer- Spring 35 and terminates in position to be viewed erence numeral I designates a case having a Vfrom the exterior of the ease I through a glass closure 2 secured by means of screws 3 to seal window 58. Preferably the movable magnet SYS- the case. The case constitutes a supporting tem is adjusted by Ineens., 0f the SCIBW 50 S0 frame for the instrument, A that the parts of the instrument are in cor- 20 A coil I5 is supported rigidly within the case, rect position and ready for operation when thel The e011' comprises a, winding s. of copper 01- indicating bar 51 is seen in the center of the i other metal wire and an iron core 1 which is Window 53- l preferably laminated as shown. The coilis se- The magnets and' 25 are Suspended with 25 cured rigidly to a coiLframe comprising plates the polesA 0f the magnates disposed on ODPOSlte -25 9 and In heldwgether by bon-,s Opposite sides of and spaced from the ends I2 and I3 ends I2 and I3 of the iron core protrude beyond 0f the Corethe coil frame. The coil frame is secured rigidiy It will be evident from the arrangement -by bolts l5 to a supporting frame is, VThe frame shown that magnetic lines of force starting from k I6 is formed of bars I1 and I8 rigidly connected the north Dole of magnet 25 Proceed aoIOSS the 30 by bolts I9. The har I8 depends. from and is iron core 1. t0 the South P016 of the magnet rigidly supported by the closure 2 by means 26 and throuh the magnet 25 t0 the north Dole of'a bolt 2|. of the magnet 26 whence they again traverse A system is movably supported from the frame the iron core 'I to the south pole of the magnet I6. The-movable system includes spaced mag- 25. Other magnetic-lines of force travel from 35 nets 25 and 26 which are secured as a unit by the north 901e 0f the magnet 25, penetrate the means of brackets 21 and 28 respectively to a. end 'I3 of the iron core 1 and follow this core plate 30. The movable system is yieldably susto the end I2 of the iron core to return to the `pended fromV the frame I6 by means of fiat south pole of the magnet 25. Other magnetic spring members 35 and 36. The spring memlines' of force travel from the north pole of 40 bers 35 and 36 are secured at one end by screws the magnet 26,'penetrate the end I2 of the iron 31 to opposite ends of the bar I1. The spring core and follow the core to the other end I3 members 35 and-36 are secured at their movto return to the south pole of the magnet 26. able ends by means of screws 38 to opposite ends It will be understood that if the magnets 25 of the plate 30. The springs 35 and 36 function and 26 are equal in intensity oi magnetization 45 as centering springs which partially support the and if the iron core 1 is exactly ait the same movable system. 'I'he coill is connected to elecdistance from the magnets then the lines of -trical conductors 31a and 38a which extend force travelingalong the iron core from one through a gland 39 in the closure 2. end to the other cancell each other. If, how- The movable system is further yieldably supever, one magnet is nearer the iron core than 50 ported by means of helical springs 45, the lower the other its lines of force are not cancelled ends of which are secured to the bracket arm 21 by the lines of force of the other magnet. and the upper ends of which are secured to a There is thus a change in the iiux through the substantially horizontally disposed center-piece iron core while the magnet is moving relative 56 I5. The center-piece 46 is supported in a subto the core. This change in ux induces an 55 40 of opposite polarity,

electro-motive force in the coil. The induced current is conducted from the coil through conductors @iii and BI.

The seismograph depends for its electro-motive force upon the change in flux in the iron core of the coil which is caused by relative motion of the magnets and iron core' thereby effecting a high degree of sensitivity of the instrument.

It will also be understood that the coil may constitute the moving system and the magnets may be connected rigidly to the frame of the. instrument if desired so long as relative motion is attained between the coil and the magnet system.

Various changes may be made within the scope of the appended claims in which it is' desired to claim all novelty inherent in the invention as broadly as the prior art permits.

We claim:

1. In a. seismograph, a frame, a coil wound on ai rigid iron core, the ends of the core protruding from the coil in a horizontal direction, means immovably securing the coil to the frame, and a movable system including magnets of large inertia, means yieldably suspending the magnets from the frame for movement in a vertical drection with the poles of the magnets disposed on opposite sides of and spaced from the ends of the core whereby the magnets are maintained substantially stationary when the frame is subjected to seismic vibrations and motion of the core relative to the magnets induces electromotive force acrossthe coil.

2. In a seismograph, a frame, complementary permanent magnets having a large inertia and dem'ng arms having confronting pole faces, the confronting poles of opposite magnets being a unit of small inertia including a coil between the arms of the magnets and wound on a rigid core extending through the coil and between the pole faces of the magnets, and means separately supporting 45 the unit and the magnets from the frame for equal relative movement toward and from each acuosa the core being normally disposed. in equally spaced relation between confronting pole faces of the opposite magnets whereby ux in the core is balanced and electromotive force is generated in the coil upon said relative movement.

3. In a seismograph, a' frame. complementary permanent magnets rigidly secured together in alignment' vertically and deilning arms having confronting pole faces,r confronting poles of opposite magnets being of opposite polarity, a' unit including a coil between the arms 4of the mag.- nets and wound on a rigid core extending through the coil and between the pole faces of the magnets, and meansl separately supporting the unit and-the magnets from the frame for equal relative reciprocating movement in a vertical plane toward'andv from and with respect to' each other throughout the extent of the core when the frame is vibrated' vertically during seismic vibrations, the core being normally disposed in equally spaced relation between confronting pole faces of the opposite magnets whereby iiux in the core is balanced and electromotive force is generated in the coil upon vertical vibration of the frame. y

4. In a seismograph. a frame, vertically spaced complementary permanent magnets of .large inertia defining arms having confronting pole faces, confronting poles of opposite magnets being of opposite polarity, means resiliently suspending the magnetsfrom the frame to form. a suspended mass of large inertia which arms remain substantially stationary when the frame is subjected to seismic vibrations, and a unit including a coil between the arms of the magnets and fixed to the" frame and wound on a rigid core extending through the coil and between the pole faces of the magnets whereby the movement of the pole faces with relation to the core is in a direction at right-angles to the axis oi' the core. I

LUDWIG W. BLAU. LOUIS STATHAM. 

